In this episode of the Leanpub Podcast, Len Epp interviews Klaus Haller, senior IT security architect and author of The Definitive Guide to Cloud Security Architecture. They explore Klaus’s career journey from software engineering into cloud security, and dive into the four pillars of cloud security: architecture, network/perimeter defenses, identity & access management, and workload/SOC tooling. Klaus explains how organizations can strengthen resilience against advanced cyber threats, the role of AI in both attacks and defenses, and the importance of quality assurance in cloud environments. He also reflects on his writing process and why documenting cloud security best practices matters for both practitioners and companies moving into the cloud. The conversation offers insights into building secure, scalable cloud systems, navigating modern cyber risks, and preparing for the future of cybersecurity. You can find the book on Leanpub at https://leanpub.com/cloud-security-architecture. This interview was recorded on August 14, 2025. The full audio for the interview is here: https://s3.us-east-1.amazonaws.com/leanpub_podcasts/FM320-Klaus-Haller-2025-08-14.mp3. The Leanpub Podcast is available on our YouTube channel at https://www.youtube.com/leanpub, in Apple Podcasts here https://podcasts.apple.com/ca/podcast/frontmatter/id517117137, and almost everywhere else people listen to podcasts. This interview has been edited for conciseness and clarity.